Add contributing.md and edit changelog.md and readme.md
Link relevant issues
Closes #391
Checklist when you are ready to request a review
[x] I have performed a self-review of my code
[ ] I have added docstrings in line with the guidance in the CIL developer guide
[ ] I have implemented unit tests that cover any new or modified functionality
[x] CHANGELOG.md has been updated with any functionality change
[x] Request review from all relevant developers
[ ] Change pull request label to 'waiting for review'
Contribution Notes
[x] The content of this Pull Request (the Contribution) is intentionally submitted for inclusion in CILViewer (the Work) under the terms and conditions of the Apache-2.0 License
[x] I confirm that the contribution does not violate any intellectual property rights of third parties
Qt contributions should follow Qt naming conventions i.e. camelCase method names.
VTK contributions should follow VTK naming conventions i.e. PascalCase method names.
Describe your changes
Add contributing.md and edit changelog.md and readme.md
Link relevant issues
Closes #391
Checklist when you are ready to request a review
Contribution Notes
Qt contributions should follow Qt naming conventions i.e. camelCase method names.
VTK contributions should follow VTK naming conventions i.e. PascalCase method names.